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So I’ve 10 weeks to train for a half ironman distance triathlon. Also, I want to beat or at least match last year’s time in the same race. The big question – is training for half ironman triathlon in just 10 weeks even doable?

sheephaven half bike elevation

Why only 10 weeks?

I originally planned to give myself at least 20 weeks for this race but life, weather, and a general lack of motivation changed that plan. Add to this that I somehow managed to think the race was on the 25th of July and NOT the actual date of the 25th of JUNE!

I realized this only 10 weeks out from the actual start date. Now keep in mind I was already starting to think I’d left myself rather short on training time anyway. When it suddenly came to light I actually had a month less than that, well you can imagine the kind of fire that got lit under my ass!

In short, I left it too long to start training, I had a month less than I thought I had, and only have myself to blame.

Which Half Ironman Race?

So I’ll be doing the Sheephaven Half Iron Distance Triathlon, located in Ireland, Donegal. I also did this same race last year, you can check out more about the race itself and my performance in this blog post – My first half ironman in 8 years: Sheephaven Half Ironman 2021.

The distances for swim/bike/run are the standard 1.9k/90K/21K. Sea swim, hilly bike with 1100m of climbing, and lumpy run.

Where I’m starting from

Over the previous winter and up to the start of the training block I have been doing a small amount of training. 1 or 2 sessions a week at most.

Currently at around 10km distance for running, and around 1hr 30min for biking before I’m blowing up. I have done absolutely no swimming since completing last year’s half ironman.

Training priorities

Training for half ironman triathlon is a tough process at the best of times. However, with just 10 weeks until race day, my training priorities will be of utmost importance. This type of thing is usually a recipe for disaster in the form of not enough training done, or doing too much too soon and getting injured along the way.

Therefore my priorities are as follows –

  1. Get the race distances plus 10-30% covered in training.
  2. After the above is complete I will focus on speed/power sessions.

What this translates to is training up to –

  • 2090 – 2470m on the swim
  • 99 – 117km on the bike
  • 23 – 27km on the run

The priority level to achieve the extended distances in training will be in the order of bike, then run, then swim.

There will be no pre-planned speed or power sessions, particularly for running, until I hit those distances. This will minimize the risk of injury which is something I need to avoid at all costs given the short timeframe.

Any speed or power sessions will be done on an as-feel basis. What that means is going hard when my body feels like doing it and NOT because I have to fulfill a particular session plan.

10 Week Training Diary

Week 1 (18th – 24th April)

  • 12.37 km run – 1:06:55
  • 48.69 km cycle – 1:46:22
  • 11.79 km run – 1:02:30
  • 54.44 km cycle – 2:06:03


  • Not much to note here, just getting back into training with some consistency. The first week completed and tired by the end of it.

Week 2 (25th April- 1st May)

  • 25.81 km cycle – 1:15:36
  • Brick Session
    • 4.62 km cycle – 14:24
    • 15.48 km run – 1:20:28 (Long run)
    • 3.58 km cycle – 14:19
  • 37.56 km cycle – 1:20:07
  • 8.25 km run – 42:49
  • 12.40 km run – 1:03:42 (5 km tempo effort – 24:26)


  • Another solid week completed.
  • Extended long run out to 15 km.
  • Building up the ability to hold the time trial position on the TT bike again.
  • 8 weeks to go!

Week 3 (2nd – 8th May)

  • 34.90 km cycle – 1:44:38
  • Brick Session
    • 5.53 km cycle – 15:49
    • 10 km run – 47:56 (Tempo run) stats->
    • 4.73 km cycle – 16:41
  • 63:41 km cycle – 2:26:32 (Long cycle TT bike, Hilly) stats->
  • 8.73 km run – 44:45


  • A little bit less this week than I would have perhaps liked but still ok.
  • The long cycle pushed out to 63 km and 800m of climbing.
  • Sub 48 min for 10km tempo run, felt good on that run so decided to push it out a bit.
  • 7 weeks to go!

Week 4 (9th – 15th May)

  • 26.68 km cycle – 1:18
  • 18.19 km run 1:36:53 stats->
  • 2000m swim (Pool) – 50:40
  • 10.20 km run – 48:39 (hilly-tempo, 10k – 47:53) stats->


  • Another week where I got less done than hoped.
  • First swim since last year’s race. I certainly felt it during and afterward. Managed 2.0k so I’m happy with that.
  • The long-run pushed out to 18 km. Quite hilly with 276m of total climbing.
  • Another sub 48 min for a 10km tempo run, happy with this run as it was a hilly 10k with 140m of climbing.
  • 6 weeks to go!

Week 5 (16th – 22nd May)

  • 20.65 km cycle – 1:09:06
  • 25.57 km cycle – 1:23:28
  • 8.23 km run – 43:28
  • 2000m swim (Pool) – 54:54
  • 81.93 km cycle – 3:11:59 (long, hilly, 971m climbing) stats->


  • Slight issue with Achilles tendon on my right leg. I have decided to pull back a little on running to let it recover.
  • Long cycle pushed out to a very hilly 81km, tough in the last few km I will admit.
  • 5 weeks to go! Half way there.

Week 6 (23rd – 29th May)

  • 27.32 km cycle – 58:16 (10 mile TT effort – 28:54) stats->
  • 25.81 km cycle – 1:19:31
  • 5.17 km run – 27:43
  • Brick Session
    • 22.92 km cycle – 56:06
    • 2.29 km run – 11:50
  • 1950m Swim (pool) – 50:06
  • 11:04 km run – 55:02


  • My right achilles still hurting for most of the week.
  • Pushed out a hard effort 10 mile TT cycle at the start of the week
  • Managed an 11k run under 5:00min km pace by the end of the week.
  • Achilles issue is definitely on the mend, starting to feel safe to run hard on it again.
  • Next week’s priority will be more running and the longest cycle of the training block!
  • 4 weeks to go!

Week 7 (30th May- 5th June)

  • 14 km run – 1:09:25
  • 36.23 km cycle – 1:28:40
  • 16.34 km run – 1:25:35 (hilly 262m climbing) stats->
  • 1800m swim (Pool) – 49:11
  • 107.67 km cycle – 4:03:46 (long, hilly, 1127m climbing) stats->


  • Achilles issue is as good as it’s going to get I think. A 14k and 16k were completed on it with no ill effect. Looking good!
  • 16 Km run was a hilly one. An overall 5:14 min km pace without pushing hard. I’ll be happy to hold that pace or faster in the race.
  • Changed my protein intake routine this week too.
  • Was taking protein after sessions but have now changed to before AND after. I think this has contributed greatly to injury recovery!
  • Big cycle of 107 km, major hill at 3 hour mark and felt good up it. After that point was really tough! Held decent speed into the wind on the flat for the last hour but it was a real battle of wills. That last hour felt like 3!
  • Very happy to get a much longer than race distance cycle done. This should hopefully stand to me on race day. The hope being I will be much fresher going on to the run than last year!
  • Priority next week is to get a 20k+ run done and a 3-hour cycle with 1200m of climbing.
  • 3 weeks to go!

Week 8 (6th- 12th June)

  • Brick Session
    • 5.36 km cycle – 12:42
    • 10.57 km run – 48:43 (10k Tempo effort – 45:24) stats->
    • 5.47 km cycle – 16:03
  • 36.04 km cycle – 1:26:18 (Hilly – 614m climbing)
  • 8.33 km run – 43:06
  • 2000m swim (Pool) – 52:49
  • 21.5 km run- 1:53:54 (Hilly – 337m climbing) stats->


  • Pushed out a decent 10k effort to start the week. Felt good and happy with 45:24 – faster than expected.
  • Got the longest run of the block done and dusted. Would have liked maybe 2k longer but it was very hilly, much hillier than the run leg of the actual race. The last 5k was torturous and I was completely spent by the end of it. Good mental preparation for whats to come on race day!
  • Did not get the longish major hill climb cycle done I had hoped to but happy overall with the week’s training.
  • 2 weeks to go!

Week 9 (13th – 19th June)

  • 45.24 km cycle – 1:48:31
  • 16.12 km run – 1:17:55 (14k tempo pace – 1:05:56) stats->
  • 24.14 km cycle – 1:16:50
  • Brick session
    • 900m swim (Lake) – 23:07
    • 6 km run – 23:07 stats->
  • 8.53 km run – 42:34


  • Very happy with 14k tempo effort. I feel my running is starting to come together. Hopefully, I’ll be able to bring a close to 5:00 min/km on race day.
  • First lake swim of the year, I’ll admit I was dreading that cold water shock. Felt ok though, done 3*300m lengths increasing the pace slightly on each one.
  • 6km run straight of the swim. Felt really good and had to hold my pace back for the first 3k. Close to 4:30 min/km pace overall.
  • Very happy with running this week but I still didn’t get my planned 3hr 1200m climbing cycle done. I really want to get that done either Monday or Tuesday next week. If I can’t get it done by then I will have to scrap it as it will be too close to race day for me. I’m hopeful though.
  • 1 bloody week to go!

Week 10 (20th- 25th June RACE WEEK)

  • 74.44 km cycle – 3:01:10 (Hilly 1261m climbing) stats->
  • Brick session
    • 27.41 km cycle – 54:11 (16.28 km TT effort – 28:24) stats->
    • 5.77 km run 27:25
  • RACE – Sheephaven Half Ironman – 5:26:14
    • swim – 34:27
    • T1 – 02:04
    • Bike – 2:55:57
    • T2 – 01:13
    • Run – 1:52:30 stats->


  • On Tuesday I finally got the 1200m altitude cycle done, and felt strong for 90% of it. Happy to have got that done.
  • On Thursday a short but harder effort brick session. Felt very good for cycle and run.
  • The race went well overall but the weather was something else! Only have Garmin stats for the run leg as that’s the only section I had my watch on.


Is 10 weeks enough time to train properly for a half ironman distance race? Probably not, particularly if starting from scratch. However, if you have a decent base of fitness then it’s just about enough to get the job done.

Saying all that though you really need to squeeze a lot of training into 10 weeks and it leaves no room for error at all. I came very close to injuring with my right achilles, it was a very close thing there at a point I will admit.

Something like 15 – 20 weeks will make a huge difference and take the pressure off a lot. It allows a much more controlled and gradual build-up in your training. Anything longer than that though has the potential to become hard to commit to and even monotonous to a point.

Overall I’m happy with the outcome, I bettered last years time by over 6 mins (in difficult conditions) so I definitely can’t complain about that.

I’ll be posting a full race breakdown very soon and I’ll include the link here when it’s up.

Michael Duffy
Michael Duffy

Fitness, health, and outdoor enthusiast! 2 decade of experience training for, and competing in different sports. Boxer, runner, road cyclist, triathlete, and XC mountain biker. More about me here.

    2 replies to "Training for Half Ironman Triathlon in 10 Weeks"

    • Prakash P

      Thank you for sharing. Inspired!

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